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.TH T_SNDVUDATA 3NSL "Aug 23, 2001"
.SH NAME
t_sndvudata \- send a data unit from one or more noncontiguous buffers
.SH SYNOPSIS
.LP
.nf
#include <xti.h>




\fBint\fR \fBt_sndvudata\fR(\fBint\fR \fIfd\fR, \fBstruct t_unitdata *\fR\fIunitdata\fR, \fBstruct t_iovec  *\fR\fIiov\fR,
     \fBunsigned int\fR \fIiovcount\fR);
.fi

.SH DESCRIPTION
.LP
This function is used in connectionless mode to send a data unit to another
transport user.  The argument  \fIfd\fR identifies the local transport endpoint
through which data will be sent,  \fIiovcount\fR contains the number of
non-contiguous  \fIudata\fR buffers and is limited to an implementation-defined
value given by  \fBT_IOV_MAX\fR which is at least 16, and  \fIunitdata\fR
points to a  \fBt_unitdata\fR structure containing the following members:
.sp
.in +2
.nf
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
.fi
.in -2

.sp
.LP
If the limit on  \fIiovcount\fR is exceeded, the function fails with
\fBTBADDATA\fR.
.sp
.LP
In  \fBunitdata\fR, \fIaddr\fR specifies the protocol address of the
destination user, and  \fIopt\fR identifies options that the user wants
associated with this request. The  \fIudata\fR field is not used.  The user may
choose not to specify what protocol options are associated with the transfer by
setting the  \fIlen\fR field of  \fIopt\fR to zero.  In this case, the provider
may use default options.
.sp
.LP
The data to be sent is identified by  \fIiov\fR\fB[0]\fR\fI\fR through \fIiov
[iovcount-1]\fR\fB\&.\fR
.sp
.LP
Note that the limit on the total number of bytes available in all buffers
passed:
.sp
.in +2
.nf
\fIiov(0).iov_len + . . + iov(iovcount-1).iov_len \fR
.fi
.in -2

.sp
.LP
may be constrained by implementation limits. If no other constraint applies, it
will be limited by \fBINT_MAX\fR. In practice, the availability of memory to an
application is likely to impose a lower limit on the amount of data that can be
sent or received using scatter/gather functions.
.sp
.LP
By default,  \fBt_sndvudata()\fR operates in synchronous mode and may wait if
flow control restrictions prevent the data from being accepted by the local
transport provider at the time the call is made.  However, if  \fBO_NONBLOCK\fR
is set by means of  \fBt_open\fR(3NSL) or  \fBfcntl\fR(2), \fBt_sndvudata()\fR
executes in asynchronous mode and will fail under such conditions.  The process
can arrange to be notified of the clearance of a flow control restriction by
means of either  \fBt_look\fR(3NSL) or the EM interface.
.sp
.LP
If the amount of data specified in  \fIiov\fR\fB0\fR\fI\fR through \fIiov
[iovcount-1]\fR exceeds the TSDU size as returned in the  \fItsdu\fR field of
the  \fIinfo\fR argument of \fBt_open\fR(3NSL) or  \fBt_getinfo\fR(3NSL), or is
zero and sending of zero octets is not supported by the underlying transport
service, a \fBTBADDATA\fR error is generated.  If  \fBt_sndvudata()\fR is
called before the destination user has activated its transport endpoint (see
\fBt_bind\fR(3NSL)\|), the data unit may be discarded.
.sp
.LP
If it is not possible for the transport provider to immediately detect the
conditions that cause the errors \fBTBADADDR\fR and \fBTBADOPT\fR, these
errors will alternatively be returned by  \fBt_rcvuderr\fR(3NSL). An
application must therefore be prepared to receive these errors in both of these
ways.
.SH RETURN VALUES
.LP
Upon successful completion, a value of  \fB0\fR is returned. Otherwise, a value
of  -1 is returned and  \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
.LP
\fBT_IDLE\fR.
.SH ERRORS
.LP
On failure,  \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTBADADDR\fR\fR
.ad
.RS 15n
The specified protocol address was in an incorrect format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTBADDATA\fR\fR
.ad
.RS 15n
Illegal amount of data.
.RS +4
.TP
.ie t \(bu
.el o
A single send was attempted specifying a TSDU greater than that specified in
the \fIinfo\fR argument, or a send of a zero byte TSDU is not supported by the
provider.
.RE
.RS +4
.TP
.ie t \(bu
.el o
\fIiovcount\fR is greater than  \fBT_IOV_MAX.\fR
.RE
.RE

.sp
.ne 2
.na
\fB\fBTBADF\fR\fR
.ad
.RS 15n
The specified file descriptor does not refer to a transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTBADOPT\fR\fR
.ad
.RS 15n
The specified options were in an incorrect  format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTFLOW\fR\fR
.ad
.RS 15n
\fBO_NONBLOCK\fR \fBi\fR was set, but the flow control mechanism prevented the
transport provider from accepting any data at this time.
.RE

.sp
.ne 2
.na
\fB\fBTLOOK\fR\fR
.ad
.RS 15n
An asynchronous event has occurred on this transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTNOTSUPPORT\fR\fR
.ad
.RS 15n
This function is not supported by the underlying transport provider.
.RE

.sp
.ne 2
.na
\fB\fBTOUTSTATE\fR\fR
.ad
.RS 15n
The communications endpoint referenced by \fIfd\fR is not in one of the states
in which a call to this function is valid.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 15n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 15n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
.LP
In the \fBTLI\fR interface definition, no counterpart of this routine was
defined.
.SH ATTRIBUTES
.LP
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.LP
\fBfcntl\fR(2), \fBt_alloc\fR(3NSL), \fBt_open\fR(3NSL),
\fBt_rcvudata\fR(3NSL), \fBt_rcvvudata\fR(3NSL) \fBt_rcvuderr\fR(3NSL),
.BR t_sndudata (3NSL),
.BR attributes (7)
